Adjustable gastric banding apparatus have provided an effective and substantially less invasive alternative to gastric bypass surgery and other conventional surgical weight loss procedures. Despite the positive outcomes of invasive weight loss procedures, such as gastric bypass surgery, it has been recognized that sustained weight loss can be achieved through a laparoscopically-placed gastric band, for example, the LAP-BAND® (Allergan, Inc., Irvine, Calif.) gastric band or the LAP-BAND AP® (Allergan, Inc., Irvine, Calif.) gastric band. Generally, gastric bands are placed about the cardia, or upper portion, of a patient's stomach forming a stoma that restricts the food's passage into a lower portion of the stomach. When the stoma is of an appropriate size that is restricted by a gastric band, food held in the upper portion of the stomach provides a feeling of satiety or fullness that discourages overeating. Unlike gastric bypass procedures, gastric band apparatus are reversible and require no permanent modification to the gastrointestinal tract.
Over time, a stoma created by a gastric band may need adjustment in order to maintain an appropriate size, which is neither too restrictive nor too passive. Accordingly, prior art gastric band systems provide a subcutaneous fluid access port connected to an expandable or inflatable portion of the gastric band. By adding fluid to or removing fluid from the inflatable portion, for example, by means of a hypodermic needle inserted into the access port, the effective size of the gastric band can be adjusted to provide a tighter or looser constriction. The level of constriction is related to the amount of fluid in the gastric band system. The level of constriction is also related to the pressure within the gastric band system.
An implantable pressure sensor for monitoring blood pressure is disclosed in U.S. Pat. No. 5,120,313 to Elftman. However, the system of Elftman is percutaneous and extends partially outward from the skin, and is thus unsuitable for complete implantation.
A previous attempt to provide a medical pressure sensor may be found in U.S. Pat. No. 5,554,113 to Novak et al. While the Novak sensor is sterilizable, it is not fully implantable and requires a percutaneous conduit.
Other attempts to provide a medical pressure sensor may be found in U.S. Pat. No. 6,024,704 to Meador et al. and in U.S. Pat. No. 5,535,752 to Halperin et al. However, although the sensors of Meador and Halperin are implantable, they are energized by an implanted battery, and both are specifically intended for use within the heart and in connection with an implanted pulse generator.
Yet another attempt to provide a medical pressure sensor may be found in U.S. Pat. No. 6,221,024 to Miesel. The sensor of Miesel utilizes an incompressible oil as a pressure transfer medium, but does not address minimizing damaged caused by thermal expansion.
Still another attempt to provide a medical pressure sensor may be found in U.S. Pat. No. 7,021,147 to Subramanian et al. The sensor of Subramanian addresses thermal expansion but limits the scope to utilizing fillers with low or negative coefficients of thermal expansion.
A prior attempt to provide pressure monitoring for a gastric banding system may be found in U.S. Patent Application Publication No. 2006/0189888 by Hassler et al. However, the pressure sensor of Hassler is specifically part of the access port, and thus does not permit the pressure sensor to be used with preexisting access ports.
Another prior attempt to provide pressure monitoring for a gastric banding system may be found in U.S. Patent Application Publication No. 2008/0221598 by Dlugos et al. However, the pressure sensors of Dlugos do not confer strain relief or puncture resistance features.
It remains desirable to monitor pressure within a gastric band system. Thus, tubing-based pressure sensors for gastric banding systems are described herein.